The present invention relates to a vinyl resin having improved properties and a curable composition containing the vinyl resin, and more particularly to a silyl group-containing vinyl copolymer having a molecular weight of 500 to 100,000, the main chain of which is substantially composed of a vinyl polymer, and which has per one molecule at least one silicon atom to which a hydrolyzable group is bonded, and which has a monomer selected from the group consisting of an acrylic acid alkyl ester and a methacrylic acid alkyl ester, the alkyl having not less than 10 carbon atoms.
Japanese Unexamined Patent Publication (Tokkyo Kokai) No. 36395/1979 discloses that a vinyl resin including a silyl group having a hydrolyzable group at the molecular ends or side chains not only has excellent glossiness, weatherability, discoloration resistance, and the like, which are characteristics of the vinyl resin itself, but also has an improved adhesion resulting from the hydrolyzable silyl group and forms a resin having excellent solvent-resistance, water-resistance, heat-resistance and weatherability and high hardness by causing a cross-linking reaction with water, particularly water in the atmosphere, even at ordinary temperature to form a fine network structure.
The present inventors have found that the properties of the silyl group-containing vinyl resin can be extremely improved by copolymerizing (meth)acrylic acid alkyl ester having not less than 10 carbon atoms with the silyl group-containing vinyl copolymer.
One of the properties improved by copolymerizing the (meth)acrylic acid ester is the abrasion resistance. The above-mentioned silyl group-containing vinyl resin is excellent in the abrasion resistance and scratch resistance in comparison with other commercially available resins since the silyl group-containing vinyl resin can be crosslinked to form a fine network structure at ordinary or low temperature or at high temperature in a short time in the state of presence or absence of a catalyst.
Furthermore, the inventors have found that the abrasion resistance and the scratch resistance are extremely improved when subjecting the above-mentioned (meth)acrylic acid alkyl ester to the copolymerization.
In the present invention, the improvement of the adhesion is a large characteristic.
The silyl group-containing vinyl resin which is disclosed in the above publication contains a hydrolyzable silyl group and accordingly, the vinyl resin is excellent in the adhesion to an inorganic material as shown in case that usual silane coupling reagents are admixed. However, the vinyl resin is insufficient in the adhesion to an organic substance. When copolymerizing a (meth)acrylic acid higher alkyl ester with the silyl group-containing vinyl resin, the adhesion to an inorganic substance is further increased and the adhesion to an organic substance is largely improved Accordingly, the silyl group-containing vinyl resin of the invention can be preferably employed in not only paints, coatings or adhesive agents used for inorganic materials but also the top coatings of organic materials such as wood, paper, plastic materials and organic paints.